Plant growth regulating composition

ABSTRACT

2-(S,S-Dihydrocarbyl) sulfonium ethanephosphonic acid compounds, and their salts and esters, are made and are useful in regulating plant growth by accelerating ripening and abscission, dwarfing, breaking dormancy as well as altering the sex ratio of flowers.

O Umted States Patent 1 [111 3,71 1,493

George et al. 1 Jan. 16, 1973 [54] PLANT GROWTH REGULATING [56] References Cited COMPOSITION UNITED STATES PATENTS [75] Inventors: Edwin Francis George, Eversley, Nr.

Basingstoke; Alan John Davidson, 3,223,754 12/1965 Colln et al. ..260/502.4 R wokingham, both f England 3,400,148 9/1968 Quimby ..260/502.4 R 3,462,439 8/1969 Popoff et al ..260/329 P Asslgfleel Imperial Chemical Industries 3,507,937 4 1970 Zimmerer ..260/502.4 R Limited, London, England 3,637,765 1/1972 Firestone ..260/947 [22] Filed: Jan. 25, 1971 Primary Examiner-Howard T. Mars [21] Appl 109569 Assistant Examiner-J0seph E. Evans AttorneyCushman, Darby & Cushman [30] Foreign Application Priority Data Feb. 10, 1970 Great Britain ..6,403/7O [57] ABSTRACT June 16, 1970 Great Britain ..29,l23/70 2-(s,s-Dihydrocarbyl) sulfoniurn ethanephosphonic acid compounds, and their salts and esters, are made Cl 360/5024 260/329 and are useful in regulating plant growth by accelerat- 260/332 3 R, 260/332.5, 260/ ing ripening and abscission, dwarfing, breaking 260501-21 260/937, 260/947 dormancy as well as altering the sex ratio of flowers. [51] Int. Cl. ..C07t 9/38, A0ln 5/00 [58] Field of Search.260/502.4 R, 947, 329 P, 332.5, 3 Claims, No Drawings PLANT GROWTH REGULATING COMPOSITION This invention relates to chemical compounds useful as plant growth regulating agents, to plant-growth regulation compositions containing them, and to methods of regulating the growth of plants.

By the term regulating the growth of plants inthe specification we mean affecting the metabolism of plants in such a way as to bring about-an economically useful change in the behavior of the plants.

According to the present-invention there isprovide'd a compound of the formula:

R OH

or a salt, ester, or anhydride thereof wherein 'X is oxygen or sulphur, the groups R and R are hydrocarbon radicals, optionally substituted, and A is a nonphytotoxic anion.

The groups R and R may be alkyl, aryl or aralkyl.

Preferably they are alkyl radicals, having preferably 1 to 4 carbon atoms. R and R may be linked, egg. so as together constitute an alkylene radical. Preferably also X is oxygen.

Suitable salts include mono salts formed for example from alkali metals or alkaline earth metals, for example sodium, potassium, or calcium salts, or from organic bases, for example mono-, di-or trialkylamines, for-example such amines in which the one, two, or-three alkyl radicals contain up to 4 carbon atoms, for example methylamine, diethylamine, or triethylamine.

.Suitable anions A include I both riionb and polyvalent anions, for example chloride, bromide, iodide and methylsulphate: any anion may be used which is not toxic to plants at the rate of application selected for use. The-choice of anion is in fact simply a matter of convenience, Convenient routes presently available for making the invention compounds produce them in the form of the bromide. If for any reason this anion is not desired it can readily be exchanged for another, e.g. the methylsulphate anion, bya variety of well-known methods, for example by the use of an ionexchange resin. Normally however there is no reason to carry out this extra step.

Examples of compounds according to the invention are given in Table I below. Generallythey are semisolids with no sharply defined melting point, or nondistillable oils.

The general formula of the compounds listed in Tablelis:

TABLE i Prepared by method of example R 4 Physical form I R a 7 Nuclear magnetic resonance spectrumin deuterium oxide -l- M.P. 133 O-. (CHalz'S- Compound No. I

CH; -CH.

8 3 2 "B 3 a E a 5 a V NO W m m mo m A w O 0 EU --8-..-. w m 50 5650 if: w 36 8 3 u awol. v wfio mo m mo N o mo mo ..8..... m m E6 E 8 3 1 .8 8 "a N A ND c WO V -NO MO m N 0 mo 8 m m emoT g s 2 3 E v 213 3 F 3 2 E. a mo NG \m a m :62 N io mov Moo 0 o mo m 8 56 m mo 60 126 s a 0 36 b 5 flflm mo 0 o o TI. .8 33 .H E .n 8 mo N o g L 8 a E Q n 50 E0 0 o o *3. .E El .8 as .w ..8.:.. m 5 i0 m 6 9: "5 Bo o \J mo vmoo o 9?: .B 3 3 .r .E E. h .w :81... m 3655 E0 E0 $43 3 2 2 3. 5 w -MO 0 o mo m mimov a O 28-..: -N O M E0 E0 d 3 5 O 3 .B 3 2 E 3. .m :81... mofifi m Ho Ho 6 wmfimwwfi Q23 5:350 E 55.53% R6888 23% .3232 2 $2 3M m m m Z 9 0 Mn 5.25am

Conveniently the compounds of the invention are applied to plants in the form of compositions, in which the active ingredient is dispersed in a carrier. The carrier may be a solid or a liquid and may additionally comprise a surface-active agent.

Solid compositions may be in the form of dusting powders or granules. Suitable solid diluents include for example kaolin, bentonite, kieselguhr,dolomite, calcium carbonate, talc, powdered magnesia, Fullers earth and gypsum.

Solid compositions may also be in the form of dispersible powders or grains comprising, in addition to the active ingredient, a wetting agent to facilitate the dispersion of the powder or grains in liquids. Such powders or grains may include fillers, suspending agents and the like.

Liquid compositions include aqueous solutions, dispersions and emulsions containing the active ingredient, if desired in the presence of one or more surface active agents. Water or organic liquids may be used to prepare solutions, dispersions, or emulsions of the active ingredient, and aqueous solutions are particularly preferred compositions, since the compounds of our invention are mostly highly soluble in water. The liquid compositions of theinvention may also contain one or more corrosion inhibitors, for example lauryl isoquinolinium bromide.

Surface-active agents, if used, may be of the cationic, anionic or non-ionic type. Suitable agents of the cationic type include for example quaternary ammonium compounds, for example cetyltrimethylammonium bromide. Suitable agents of the anionic type include for example soaps, salts of aliphatic monoesters of sulphuric acid, for example sodium lauryl sulphate; and salts of sulphonated aromatic compounds, for example sodium dodecylbenzenesulphonate, sodium, calcium, and

ammonium lignosulphonate, butylnaphthalenesulphonate, and a mixture of the sodium salts of diisopropyland triisopropylnaphthalenesulphonic acid. Suitable agents of the nonionic type include, for example, the condensation products of ethylene oxide with fatty alcohols such as oleyl alcohol and cetyl alcohol, or with alkyl phenols such as octylphenol, nonylphenol, and octylcresol.

Other non-ionic agents are the partial esters derived,

from long chain fatty acids and hexitol anhydrides, for example sorbitol monolaurate; the condensation products of the said partial esters with ethylene oxide, and the lecithins.

The compositions which are to be used in the form of aqueous solutions, dispersions or emulsions are generally supplied in the form of concentrates containing a high proportion of the active ingredient or ingredients, the concentrate being diluted with water before use. These concentrates are usually required to withstand storage for prolonged periods and after such storage to be capable of dilution with water in order to form aqueous preparations which remain homogeneous for a sufficient time to enable them to be applied by conventional spray equipment. In general, concentrates may conveniently contain from 10 to 85 percent and preferably from 25 to 60 percent byweight of active ingredient. Dilute preparations ready for use may contain varying amounts of the active ingredient, de-

pending upon the purpose for which they are to be used; however, dilute preparations suitable for many uses contain between 0.01 percent and 10.0 percent and preferably between 0.1 and 1 percent by weight of active ingredient.

In another aspect, the invention provides a method of regulating the growth of plants, which comprises applying to the plants, or to the locus of the plants, a compound of the foregoing formula.

The rate of application of the compound will depend upon a number of factors, for example, the particular plant species to be treated, and the particular compound chosen for use. In general, however, a rate of application of from 0.1 pounds per acre to 20 pounds per acre is suitable. A preferred rate of application is from 0.5 to 4 pounds per acre.

The useful effects brought about by applying the compounds of the invention to plants include the accelerated ripening of fruits e.g. olives and coffee berries; the de-greening of citrus fruits; the acceleration of abscission; the retardation of growth and dwarfing of plants; the breaking of dormancy in buds, shoots, tu-

bers, corms and rhizomes; improving germination and after-ripening of certain seeds; altering the sex ratio of flowers in certain plants, e.g. cucurbits; and stimulating the flowering of some plants, for example pineapples.

The compounds can also be used to stimulate the flow of latex tapped from rubber trees. For this purpose the compounds are applied to the bark of the rubber tree near the cut which is made to tap the latex.

In a further aspect the invention provides processes for the preparation of the foregoing compounds.

In one process, a 2-halogenoethylphosphonic or thiophosphonic acid or ester is reacted with a dihydrocarbyl sulphide according to the scheme below:

In the foregoing scheme, Y represents chlorine, bromine, or iodine, R and R represents hydrocarbyl radicals, R and R represent hydrogen or hydrocarbyl and X oxygen or sulphur. The anion Y" may be exchanged for some other anion if desired, by means well known to those skilled in the art, for example by use of ion-exchange resins. This process is illustrated in Example 2.

In another process, a 2-halogenoethylphosphonic 1 acid or ester is reacted with an alkali metal hydrocarbyl sulphide to give a 2-hydrocarbylthioethyl phosphonic acid or ester.

Y-CHiCIIz-P(0R )(OR Ms R n s-cHgomi monmoRo M+Y- In the second stage the product of this reaction is reacted with a hydrocarbyl halide, preferably a bromide.

This process is illustrated in Example 4.- It must be conducted at moderate temperatures, i.e. below 50 C. and preferably at from 35 C. to room temperature. At higher temperatures, for example if thereaction mixture is heated under reflux, the product obtained is the hydrocarbyl thioethyl phosphonic or thiophosphonic mixture of methanol 3 8 g. and water (6.6 g.) and left to stand for 6 days at room temperature. Solvents were removed at 45 under reduced pressure and the residue was dried in vacuo to give a colourless oil. This was repeatedly extracted with dry ether to leave Z-dimethylsulphonioethylphosphonic acid bromide as a white crystalline solid (yield 8.4 g.; 33 percent) mp 133-6 half ester, or, if excess hydrobromic acid is used, the

free acid.

A fourth process is represented by the following scheme.

0. .olia c CH2+N;P(0)(OR NZsomomi 0 OR OR3 H/ In scheme B, the. symbols R, R and R represent alkyl radicals, while Z represents the anion of a strong acid, for example chloride bromide or methosulphate. A drawback of this process is that it gives very poor yields.

The compounds and processes of the invention are illustrated by the following Examples in which all proportions are by weight except where otherwise stated.

EXAMPLE I EXAMPLE 2 This illustrates analternative method of preparation of Compound No l ofTable I.

Z-Bromoethylphosphonic acid (l8.9g., 0.1M) and dimethyl sulphide (6.2 g., 0.1 M) were disolved in a (C4HIZBI'PSO3ECCIUII'CS C, 19.1; I -I', 4 8 P l2.4; ionic Br, 3 1.9; total Br, 31.9 percent. Found C, 19.3; H, 5.3; P 12.8; ionic Br, 33.2; total Br 32.3 percent) EXAMPLE 3 This example illustrates the preparation of 2- dimethylsulphonioethylphosphonic acid bromide, dimethyl ester (compound No. 3 of Table 1) in a two stage process.

a. Preparation of Z-Methylthioethane phosphonate, dimethyl ester.

A solution of sodium ethoxide in ethanol from sodium (12.7g.) and dry ethanol (600 ml.), was cooled to 0 and allowed to react with an excess of methane thiol for 10 minutes. On warming to room temperature, unreacted methane thiol distilled off. Addition of 2- bromoethyl dimethylphosphonate g.) to the cooled solution resulted in a rapid exothermic reaction which immediately began to deposit sodium bromide as a dense white precipitate. The reaction was stirred for-l 8 hours at room temperature, the solution filtered and the filtrate evaporatedto give a white viscous paste containing a large amount'of inorganic material. 2- Methylethioethyl dimethylphosphonate (72 g., 89 percent) was isolated as a mobile oil by extraction into dry ether and evaporation of the solvent. (b) Preparation of 2-dimethylsulphonioethyl phosphonic acid bromide, dimethyl ester.

Methyl bromide (25 ml.) was reacted with 2- methylthioethyl dimethylphosphonate (6 g.) at 4.5 for 18 hours giving the corresponding dimethylsulphonium salt, as a white semi-solid, in 92- percent yield.

EXAMPLE 4 This Example illustrates the preparation of methyl hydrogen Z-dimethylsulphonioethyl phosphonate bromide (Compound No. 4 of Table I). Dimethyl 2- methylthioethylphosphonate 7.6 g.,0.04M) and 46 percent hydrobromic acid (7.8 g.,0.04M) were stirred together for 6 hours at 35 Water was removed at 45 under reduced pressure and the residue was dried in vacuo over potassium hydroxide. The remaining oil was extracted repeatedly with dry ether to leave methyl hydrogen 2-dimethylsulphonioethylphosphonate bromide as a white semi-solid (yield 6.0 g., 55 percent) EXAMPLE 5 This Example shows the biological activity of compounds according to the invention.

Tomato plants growing in potting compost were sprayed when approximately 4 inches high with a 0.5 percent w/v aqueous solutions of Compounds 1, and 3 l2.

The solutions also contained 0.05 percent by weight of a surface-active agent sold under the name of Lissapol NX (Lissapol is a Registered Trade Mark for a surface-active agent comprising a condensate of ethylene oxide with p-nonyl phenol). Two days after spraying, the leaves of all treated plants were found to be epinastic, whereas plants sprayed with 0.05 percent Lissapol NX or untreated, showedno such effect.

EXAMPLE 6 This Example illustrates the abscission of leaf petioles in Coleus plants induced by application of a compound according to the invention.

Coleus plants were grown in 3 inch pots of compost until approximately 6 inches high. Some of the leaf blades were then removed leaving petiole stumps (approximately one-half to three-quarter inch in length) attached to the main stem. The plants were then sprayed with a 0.5 percent w/v aqueous solution of 2- dimethylsulphonioethylphosphonic acid bromide (compound No. 1 of Table I) containing 0.05 percent of Lissapol NX. Two days after treatment the number of debladed petioles which had fallen off the stern of treated and untreated plants was counted with the following results:

Percent petioles abscissed Plants treated with Z-dimethylsulphonioethylphosphonic acid bromide Control, untreated plants EXAMPLE 7 This Example illustrates the use of compounds of the invention in loosening citrus fruit.

Tests were conducted on miniature orange trees (Calamondins-Citrus mitis) grown in the greenhouse. Ten ripe fruits were painted with each test solution and attachment forces measured six days after treatment. The test solutions consisted of water, and invention compound and 0.1 percent Lissapol NX wetter.

This Example illustrates the use of compounds of the invention in loosening oranges, variety Salustiana in Spain Thirty ripe oranges (seven or eight from each of four trees) were painted with an aqueous solution of a compound of the invention. Each solution also contained 0.1 per cent of the wetting agent Lissapol NX. Eight days after application of the compound, the thirty treated fruits were pulled from the tree using a pushpull guage which measured the force necessary to separate the fruit from the fruit pedicel. In a control experiment, using 60 oranges from eight trees, the treatment used was an aqueous solutions containing 0.1 percent Lissapol NX, only. Results are given below.

Compound No. Concentration Mean Pull force necessary Ind Control EXAMPLE'9 This Example illustrates the use of compounds of the invention in loosening blackcurrants. Blackcurrant bushes in aSussex orchard were sprayedoverall with aqueous solutions of the invention compounds containing 0.1 percent Lissapol NX wetter. The bushes were gently shaken 5 days after spraying, and the percentages of fruit and leaf drop were assessed visually. Results are given below.

Com ound No. Concentration Fruit Leaf (Tab e 1) ppm drop drop 4 5000 70 5 2000 5 3 5000 50 5 2000 40 5 1 5000 80 5 2000 80 5 Control l 5 EXAMPLE 10 5 sured with a push-pull gauge. Results are given below.

Compound No (Table I) Mean force (Kg) required to remove fruit at indicated application rate of chemical 5000 ppm 2000 ppm 500 ppm 1 0.74 0.89 1.1 18 8 0.16 0.93 0.91 4 0.95 1.06 1.02 6 1.53 0.95 0.89 9 1.06 1.22 1.30 Control 1.48

EXAMPLE 11 This Example illustrates the use of compounds of the invention to increase the proportion of female flowers in cucurbit plants, thereby increasing the fruit bearing potential of the plants.

Cucumber plants (Cucumis sativus, variety Suttons Improved Telegraph) were sprayed with aqueous solutions of the invention compounds at the stage of growth in which two leaves are fully expanded and the third leaf is half expanded. The concentration of the invention compounds was 1,000 ppm. There were four replicate plants per treatment. The plants were grown on to maturity and the number of male and female flowers counted. Results are given below.

Compound N0. Male Flowers Female Flowers (Table l) 3 55.9 44.1 8 80.8 19.2 Control 89.8 10.5

EXAMPLE 12 This Example illustrates the use of compounds of the present invention in ripening tomatoes.

Tomatoes (Lycopersicon esculentumlofan Italian canning variety were grown in the field in Valencia, Spain. Seven days before harvest they were sprayed with aqueous solutions of the invention compounds containing 0.1 percent Lissapol NX wetter. Assessments of ripeness were then made 3 days later, and again seven days later, just after harvest. Tomatoes were classified visually as red, pink/red, pink or green/pink and a ripeness index calculated as follows Ripeness index red fruits 0.75 pink/red fruits) 0.5 pink fruits) 0.25 (%green/pink fruit) The table below gives the percentage increase in ripeness index over untreated controls at the same stage of development. It should be noted that the 3 day assessment is inherently less accurate than the 7 day assessment because the fruits are not removed from the plant.

% increase in Ripeness index after 7 days (harvest) Compound No Concentration (Table l) ppm 3 days I000 5000 2000 2000 l 000 i000 2000 1000 2000 1000 2000. 1000 We claim: 1. COmpounds of the formula 

2. The compound of claim 1 which is 2-dimethylsulphonioethyl phosphonic acid bromide.
 3. A compound according to claim 1 wherein R1 and R2 are lower alkyl and R3 and R4 are hydrogen or lower alkyl. 